The present invention relates to a semiconductor device and more particularly to a semiconductor device having high reliability and high speed responsibility.
The present invention relates to a semiconductor device wherein a metallization film layer constituting a logic circuit disposed on a semiconductor chip is made of an improved metallization material.
Pure Al or Al-Si type alloy has been used as a material for a metallization film layer constituting a logic circuit disposed on a semiconductor chip because the pure Al or Al-Si type alloy has high workability.
Miniaturization of a metallization film layer has advanced in recent years to provide higher integration density of the semiconductor chip and the formation of the metallization film layer; a metallization film layer with a thickness about 1 .mu.m, and having a metallization line of below 1 .mu.m are now necessary.
However, the reduction of the cross-sectional area of the metallization film layer disposed on the semiconductor chip has caused serious problems such as the drop of the response speed of the circuit of the semiconductor device due to the increase in a conducting delay time, the increase in an exothermic quantity of the semiconductor chip, the drop of the metallization life due to the progress of electro-migration with the increase in an electric current density on the semiconductor chip, and so forth.
Therefore, the metallization film layer material including the electrode portion material must have low electric resistance, high heat-resistance and high resistance to electro-migration. Furthermore, the metallization film layer material must be excellent in corrosion resistance, too, with the decrease in the film thickness of the metallization film layer.
However, the materials for conventional Al type metallization film layers including the materials for the electrode portion of the semiconductor device have high electric resistance and are not free from the problems with respect to heat resistance and electro-migration resistance.
To avoid these problems, Japanese Patent Laid-Open No. 294838/1986 describes a Cu type metallization film layer material for the semiconductor device having higher electric conductivity, higher heat resistance and higher electro-migration resistance than Al type metallization film layer material.
In other words, the electric resistance of Cu is about 2/3 of that of Al and the melting point (1083.degree. C.) of Cu is 400.degree. C. or more higher than that (660.degree. C.) of Al. Moreover, the conducting life of Cu material due to the progress of electro-migration is incomparably higher than the conducting life of the Al material.
Accordingly, if a semiconductor device is fabricated by use of Cu material for the metallization film layer disposed on the semiconductor chip, high speed responsivity and high reliability of the semiconductor device can be improved.
However, Cu is not free from the problems of oxidation resistance and corrosion resistance. Since the protective property of oxidation by an oxide film such as CuO and Cu.sub.2 O formed on the surface of Cu is lower than that of Al, Cu is more susceptible to high temperature oxidation and is more easily corroded in an oxidizing solution such as nitro-hydrofluoric acid mixture.
The metallization film layer material disposed on the semiconductor chip for the semiconductor device must have high corrosion resistance because it is exposed to high temperature gas atmosphere and to an oxidizing aqueous solution environment such a nitro-hydrofluoric acid mixture in the fabrication process of the semiconductor device and is subjected to a moisture reliability test under high temperature and high humidity conditions.
It is therefore an important technical problem to improve the corrosion resistance of the metallization film layer material for the semiconductor device while satisfying its need for high electric conductivity, heat resistance and electro-migration resistance.